string - How to Read and Mark(Highlight) a pdf file using C# -

I have a PDF file which I am reading from page as a string page. Now from page 4 in my PDF Billing information is included. For example, this is under the Billing Information section: - There is a local billing information and the other is STD billing information. If the user wishes to validate local billing information as per my requirement, my code should be read and validate all the local billing data, if any data (line) verification fails, then exposing it to the line of PDF file needed.

Here my code is C #

  public static string ReadPdfFile (string fileName) {stringbilder text = new stringbiller (); If (file example (filename)) {pdf reader pdf reader = new pdf reader (filename); {ITextExtractionStrategy Strategy = New SimpleTextExtractionStrategy () for (int page = 2; page & lt; = pdfReader.NumberOfPages; page ++); String current text = pdfext extractor Gatetextfram (PDF reader, page, strategy); CurrentText = encoding.UTF8.GetString (ASCIIEncoding.Convert (encoding.default, encoding.UTF8, encoding.default.NETettes (current text)); Text.Append (currentText); } PdfReader.Close (); } Return text. Toasting (); }}